Beware the Hints: Check and Double Check

Featured imageWith mostly recent and current European ancestry, my newly minted Ancestry DNA results only produced 11 Shared Ancestor hints.  One of which, belonging to Rebecca, suggested our common ancestors are Michael Warren and Catherine Henton, my 7th great-grandparents.  Ancestry classified us as 5th to 8th Cousins with confidence rated as, ‘Good.’

Rebecca happens to have a kit at FTDNA and Gedmatch.  FTDNA reports we share an 8.75 cM segment and Gedmatch reports a 10.1 cM shared segment on chromosome 1.  As Rebecca is also a multi-generational tester, and our Warren/Henton match is through her tested father, I checked for a match with him.  Unfortunately, I did not match her father, nor did either of my maternal aunts who are also Warren/Henton descendents.

Using the FTDNA Chromosome Browser, I entered myself and my aunts, and discovered Rebecca and I did share a segment on chromosome 1 with my Aunt Diane at 7.68 cM.  Gedmatch reported a 7.7 cM match between myself, Diane and Rebecca.

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In this case Ancestry got it wrong.  We clearly couldn’t be related through her father.  Also, as Rebecca does not match my father or either grandmothers, the match would have to be through her mother and my maternal grandfather.  Rebecca elaborated that her mother’s family is mostly fairly recently immigrated Scottish and Irish.  My maternal grandfather does have Scottish and Northern Irish ancestors, all of which have been in America prior to the Revolutionary War.  Short of a miracle, we are unlikely to ever discover any connection.

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Ancestry provided another set of matches, one being a 3-4th cousin and the other a 4th-6th cousin with the confidence marked as ‘Extremely High’.  In this instance, the testers were already known: CAK is my tested grandmother’s second cousin and Harold is his son.  We are all descendents of Henry Kane and Catherine Forrestal of Castlebar, Ireland.

Neither have transferred to FTDNA, but both kits have been uploaded to Gedmatch.  At Gedmatch, I share 133.4 cM total with CAK with a longest segment of 50 cM.  With Harold I share 71.1 cM total and 33.1 cM longest.  Following the DNA, in conjunction with our paper trail, my father shares with CAK 125.6 cM total and 50.2 cM longest. He shares  73.8 total  and 33 cM longest with Harold.  My grandmother, CAK’s 2nd cousin, shares 266.4 cM total and 119.9 longest with him and 132.3 cM total and 37.3 longest with his son Harold.  Not only do our family trees match, but our DNA falls within the expected ranges for our relationships and we have other Castlebar Kane cousins who also match in the same place.   In this case, Ancestry seems to have gotten it right.

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Comparison between Paternal grandmother, CAK and Harold.

I love the idea of Ancestry’s ability to auto search through trees and to find common ancestors.  Although Rebecca is on my FTDNA match list and has two in-common surnames listed, I never spent any time looking into the match as it is so small. Had Ancestry not provided a pre-prepared ‘connection’ I may have never examined the match at all.  Unfortunately, it is clearly wrong, although it appears perfectly reasonable at face value. I am not so sure how many of Ancestry’s customers realize how important it is to follow up these ‘hints’ with other tools that let you directly compare common segments.

I have contacted each of my new matches with Shared Ancestor Hints and urged them to upload their raw data to Gedmatch.   If you are an Ancestry customer and have not already done so, instructions for downloading your raw data from Ancestry are here.  Instructions for uploading your raw data to Gedmatch are here.  Gedmatch is free and gives access to testers from 23andMe and FTDNA in addition to Ancestry.  While taking the time and trouble to compare and triangulate your matches may be more work, it is also reassuringly concrete and a reliable way to accurately trace your .family tree.


9 thoughts on “Beware the Hints: Check and Double Check

      • Although I don’t use Ancestry DNA (I have used FTDNA and 23andme), I found your analysis of their results versus “reality” fascinating. I don’t think it’s any different for the other companies except that they don’t link you to someone’s tree. But the estimates are just as likely to be erroneous. At least in my experience.

        Liked by 1 person

      • I find FTDNA (not at 23and Me) to predict immediate relatives well, but 2-4th cousins are almost always 4th or further out. With the nature of recombination that is inevitable and thus the range. My concern with the Shared Hints at Ancestry is users are accepting the hints as facts since there is no tool to compare segments. I’m not familiar with the 23andMe interface, but at FTDNA and of course at Gedmatch e can compare segments which is vital to accuracy.

        Liked by 1 person

      • Well, that’s the problem with too many people—they accept as fact what they see on Ancestry trees, DNA related or not. I don’t like 23andme because it is almost impossible to contact matches. FTDNA is my favorite, but as an Ashkenazi Jew, I’ve found its estimates grossly distorted beyond the second cousin range.

        Liked by 1 person

      • Well, he focuses on just those who share his surname, which is itself unusual. And I think he was able to get many family members to test. I’ve not been as lucky!

        Liked by 1 person

      • Yes, he has dozens at this point, I think, but when they are all as closely related as they are I imagine that cause its own set of problems.

        I have been recruiting family to test as well and as we have discussed before it is difficult and expensive but well worth it. I take it one test at a time 🙂

        Liked by 1 person

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